copy from pytouhou/utils/vector.py
copy to pytouhou/utils/vector.pyx
--- a/pytouhou/utils/vector.py
+++ b/pytouhou/utils/vector.pyx
@@ -12,32 +12,38 @@
 ## GNU General Public License for more details.
 ##
 
-from math import sqrt
+from libc.math cimport sqrt
 
 
-class Vector(list):
-    def __init__(self, data=None):
-        list.__init__(self, data or [0] * 3)
-
-
-    def __add__(self, other):
-        return Vector([a+b for a, b in zip(self, other)])
+cdef class Vector:
+    def __init__(self, float x, float y, float z):
+        self.x = x
+        self.y = y
+        self.z = z
 
 
-    def __sub__(self, other):
-        return Vector([a-b for a, b in zip(self, other)])
+    cdef Vector sub(self, Vector other):
+        cdef float x, y, z
+
+        x = self.x - other.x
+        y = self.y - other.y
+        z = self.z - other.z
+
+        return Vector(x, y, z)
 
 
-def cross(vec1, vec2):
-    return Vector([vec1[1] * vec2[2] - vec2[1] * vec1[2],
-                   vec1[2] * vec2[0] - vec2[2] * vec1[0],
-                   vec1[0] * vec2[1] - vec2[0] * vec1[1]])
+cdef Vector cross(Vector vec1, Vector vec2):
+    return Vector(vec1.y * vec2.z - vec2.y * vec1.z,
+                  vec1.z * vec2.x - vec2.z * vec1.x,
+                  vec1.x * vec2.y - vec2.x * vec1.y)
 
 
-def dot(vec1, vec2):
-    return vec1[0] * vec2[0] + vec2[1] * vec1[1] + vec1[2] * vec2[2]
+cdef float dot(Vector vec1, Vector vec2):
+    return vec1.x * vec2.x + vec2.y * vec1.y + vec1.z * vec2.z
 
 
-def normalize(vec1):
-    normal = 1 / sqrt(vec1[0] * vec1[0] + vec1[1] * vec1[1] + vec1[2] * vec1[2])
-    return Vector(x * normal for x in vec1)
+cdef Vector normalize(Vector vec):
+    cdef float normal
+
+    normal = 1 / sqrt(vec.x * vec.x + vec.y * vec.y + vec.z * vec.z)
+    return Vector(vec.x * normal, vec.y * normal, vec.z * normal)